Ion acceleration and direct ion heating in magnetic reconnection were experimentally observed during counterhelicity merging of two plasma toroids. Plasma ions are accelerated up to the order of the Alfvén speed through contraction of reconnected field lines with three components. The significant ion heating (from 10 up to 200 eV) is attributed to direct conversion of magnetic energy into ion thermal energy, in agreement magnetohydrodynamic and macroparticle simulations.

• Received 10 October 1995

DOI:https://doi.org/10.1103/PhysRevLett.76.3328